1. Field of the Invention
The present invention relates to a pressure-sensitive adhesive composition suitably used for an optical filter of a plasma display and an adhesive sheet prepared by forming the same.
2. Description of the Related Art
A plasma display is a device in which molecules of sealed rare gas are excited by plasma discharge between electrodes to generate a UV ray and excite a fluorescent material by the UV ray generated and in which a light in a visible light region is emitted from the fluorescent material excited to thereby display images. Since light emission is carried out by making use of plasma discharge in the above plasma display, an unnecessary electromagnetic wave having a frequency band of 30 to 130 MHz leaks to the outside, and therefore the electromagnetic wave is requested to be inhibited to the utmost from leaking so that an adverse effect is not exerted on other instruments (for example, information processing devices and the like).
Disclosed in, for example, a patent document 1 is an electroconductive mesh film which is used for an optical filter of a plasma display and in which an electroconductive fiber mesh prepared by constituting electroconductive fibers into a mesh form or an electroconductive metal mesh produced by metal such as a copper foil and the like is formed.
Further, in an optical filter of a plasma display, a contrast enhancing film is used as well in order to enhance a contrast of a screen (refer to, for example, a patent document 2).
However, when a metal mesh is used as an electromagnetic wave shielding means for an electromagnetic wave shielding film in an optical filter of a plasma display, a moire phenomenon is brought about by mutual interference between a metal mesh and a contrast enhancing film, and therefore an anti-glare film has had to be further disposed in order to prevent the moire phenomenon. In this case, the number of the films to be stuck in order to form an optical filter is increased, and therefore the problems that the optical filter is increased in a cost and reduced in a productivity and that the optical filter is increased as well in a thickness have been involved therein.    Patent document 1: Japanese Patent Application Laid-Open No. 226732/2004    Patent document 2: Japanese Patent Application Laid-Open No. 272161/2007